A major contributing factor to the Apollo 1 fire was they didn't merely have a pure oxygen atmosphere, but a pressurized pure oxygen atmosphere. Pressurized a

A major contributing factor to the Apollo 1 fire was they didn't merely have a pure oxygen atmosphere, but a pressurized pure oxygen atmosphere. Pressurized above 1 atmosphere, for testing purposes. In space they would have operated with a substantially lower pressure; I believe about 1/5th of atmospheric pressure. A low pressure pure oxygen environment is still a fire hazard relative to regular air with the same partial pressure of oxygen, but it's not nearly as dangerous as a pressurized oxygen atmosphere.